THE EFFECTS OF SPINAL ANESTHESIA, PERIPHERAL NERVE BLOCKS OR FENTANYL ADMINISTRATION ON THE STRESS RESPONSE IN DOGS UNDERGOING STIFLE SURGERY

Introduction: The present study evaluates the stress response in dogs undergoing stifle surgery receiving different analgesic protocols. Methods: After committee approval, forty-five client-owned healthy dogswere divided into three groupswhich were randomly assigned to receive fentanyl VRI, spinal anesthesia, or femoral and sciatic nerve block as part of a standard anesthetic protocol during stifle surgery. Fifteen healthy dogs undergoing non invasive orthopedic diagnostic procedures under anesthesia were included as control group. Blood samples were collected on arrival at the hospital (T0), induction of anesthesia (T1), extubation (T2), and one hour after extubation (T3). Serum cortisol was analyzed in all samples. Dysphoria and pain scoreswere evaluated postoperatively by a blind researcher. Results: In control group cortisol was 2.9 ± 1.6, 3.6 ± 2.0, 2.4 ± 1.2, 1.8 ± 1.0 g/dL at T0, T1, T2 and T3 respectively. In spinal anesthesia and peripheral nerve block groups cortisol was 4.0 ± 1.7, 4.1 ± 2.1, 5.1 ± 2.4, 3.3 ± 2.0 and 3.7 ± 2.0, 4.3 ± 2.2, 3.2 ± 2.1, 3.1 ± 2.1 g/dL at T0, T1, T2 and T3 respectively. In fentanyl group cortisol was significantly higher at T2 and T3 compared to the other groups (3.6 ± 0.7, 5.3 ± 1.7, 9.2 ± 1.6, 10.8 ± 1.5 g/dL at T0, T1, T2 and T3 respectively). Dysphoria and pain scores were higher in fentanyl group compared to the other groups. Conclusion: Spinal anesthesia and peripheral nerve blocks reduce the stress response in dogs improving postoperative outcome.